Variable vanes

ABSTRACT

An annular cascade of variable setting vanes in a compressor includes an annular row of vanes extending inward from the case and mounted on shafts extending through the case, each vane having a disk engaging the case through a bushing. Additional bushings are provided between the shaft and the case and on the exterior of the case. A washer bearing against the exterior bushing is held by a nut threaded onto the shaft and the nut is retained against rotation by a locking cup washer interlocked rotatively with the shaft. The washer and a vane actuating arm also interlocked rotatively with the shaft are retained by a cap screw threaded into the outer end of the shaft. The interior of the case preferably has a circumferential recess to receive the interior bushings of all the vanes and the interior bushing for each vane is preferably of generally rectangular outline and of varying thickness to accord with the varying spacing between the disk and the cylindrical or conical interior surface of the recess.

United States Patent [191 Nickles VARIABLE VANES [75] Inventor? Lawrence H. Nickles, Indianapolis,

Ind.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Nov. 1, 1972 [21] Appl. No.: 302,746

[52] US. Cl 415/147, 415/160 [51] Int. Cl. .1 F04d 29/52, F04d 27/00 [58] Field of Search 415/147, 149, 160

[56] References Cited UNITED STATES PATENTS 2,930,579 3/1960 Boyd et a1 415/160 3,367,628 2/1968 Fitton 415/160 3,538,579 11/1970 Sprenger 415/160 3,542,484 11/1970 Mason 415/147 3,652,177 3/1972 Loebel 415/160 3,674,377 7/1972 Trappmann 415/160 3,695,777 10/1972 Westphal et al...; 415/160 [451 Jan. 29, 1974 Primary Examinerl-lenry F. Raduazo Attorney, Agent, or Firm-Paul Fitzpatrick [5 7 ABSTRACT An annular cascade of variable setting vanes in a compressor includes an annular row of vanes extending inward from the case and mounted on shafts extending through the case, each vane having a disk engaging the case through a bushing. Additional bushings are provided between the shaft and the case and on the exterior of the case. A washer bearing against the exterior bushing is held by a nut threaded onto the shaft and the nut is retained against rotation by a locking cup washer interlocked rotatively with the shaft. The washer and a vane actuating arm also interlocked rotatively with the shaft are retained by a cap screw threaded into the outer end of the shaft. The interior of the case preferably has a circumferential recess to receive the interior bushings of all the vanes and the interior bushing for each vane is preferably of generally rectangular outline and of varying thickness to accord with the varying spacing between the disk and the cylindrical or conical interior surface of the recess.

4 Claims, 5 Drawing Figures VARIABLE VANES This invention was made inthe course of work under a contract with the Department of Defense.

My invention is directed to improvements in variable setting vane structures such as are used in turbomachines and, while capable of other uses, is particularly directed to the improvement of such structures in axialflow compressors.

Many arrangements of variable setting vane cascades have been'proposedfor compressors and other turbomachines. The purpose of suchis to adapt the operation of the machine to varying levels of flow. Examples which may be noted are described in US. patents as follows: Neumann No. 2,933,234, Apr. 19, 1960; Hall No. 2,972,441, Feb. 21, 1961I; Johnsn'No. 3,303,992, Feb. 14, 1967; and Mason No. 3,542,484, Nov. 24, 1970.

My invention is directed to providing a structure which is more feasible to manufacture and assemble and one which is more reliable and longer lasting in service than those previously known.

Features of my invention include a simple arrangement by which one threaded fastener adjusts the tightness of the bushings'which serve as bearings for the rotatable vane and another threaded fastener cooperates with means to lock the first threaded fastener in position and retains an actuating. arm for the vane; and,

' preferably, an improved arrangement of the portion of the case confronting the vanes and the bushings between that portion and the vanes to greatly simplify ma chining of the compressor case.

Other objects andadvantages of the invention-willbe apparent to those skilled inthe-art from the succeeding detailed description of preferred embodiments of the invention.

Referring to the drawings,

FIG. 1 is a sectional view, taken in a plane containing the axis of rotation of the compressor, of a portion of a variable setting angle compressor vane arrangement.

FIG. 2 is a fragmentary sectional view taken on the plane indicated by the line 2-2 in FIG. 1.

FIG. 3 is a fragmentary cross-sectional view taken on the plane indicated by the line.3--3 in FIG. 1.

FIG. 4 is a fragmentary view taken on a plane similar to that of FIG. 1 showing a preferred arrangement of vane bushings.

FIG. 5 is a fragmentary cross-sectional view of the same taken on the plane indicated by the line. 5--5 in FIG. 4. a

Referring to the drawings, FIG. 1 illustrates a portion of a compressor including a generally conical compressor case 2 which, as is often the case, converges toward the high pressure or discharge end of the compressor. The compressor case includes a thickened section 3 defining a mounting ring or support for an annular cascade of variable setting angle vanes 4. Each vane comprises an airfoil or fluid-directing portion 6, only a portion of'which is shown, the vane in this case being preferably cantilevered; that is, free from any positive support at its radially inner end. At the radially outer end of the span of the vane a disk 7 integral with the vane bears against a bushing 8 mounted in a counterbore 10 in the inner surface of the compressor case. The counterbore is concentric with a bore 11 extending through the case, and specifically through the support portion 3. The vane also includes a shaft 12 integral with the disk 7 which extends through the case. Shaft 12 includes ajournal portion 13 which is mounted in a cylindrical bushing or sleeve 14 fitted within the bore 11. Bushing 14 may be split to provide for its installation on shaft 12.

A washer-shaped outer bushing 15 is disposed between a flat surface 16 on the exterior of the case and a thrust washer 18 disposed around the shaft 12. The shaft 12 has an outer threaded portion 19 of greater diameter than the journal 13 but of slightly smaller diam eter than the bore 11 so that it can be inserted through the case. A nut 20 threaded ontothe outer portion of the shaft is run down to tighten the nut against washer 18 to produce the desired degree of tightness of fit on the thrust bearings defined by disk 7 and bushing 8 and by surface 16 and bushing 15. These bushings, and also bushing 14, are of a resilient elastomeric material which has low surface friction such as a suitable variety of polyimide; for example, that sold by DuPont under the trademark Vespel.

The extreme outer end portion 22 of shaft 12 is milled away to provide flats 23 (FIG. 2) thus defining a portion of noncircular cross-section with which a locking cup washer 24 cooperates so that the washer is nonrotatable on the shaft. An actuating arm 26 has a generally rectangular opening 27 whichfits on the noncircular portion of the shaft so that the arm is nonrotatable on the shaft. Preferably, the clearance between the opening and the flats is slight, the clearance being exaggerated for clarity in the drawings. A minimum of relative rotation between the actuating arm and shaft is preferable.

The shaft portions 19 and 22 have a threaded internal bore 28 which receives a cap screw 30. This cap screw,

acting through a washer 31, presses on arm 26 when tightened and thus presses the locking cup washer 24 down onto the hexagon nut 20. The washer thus has an interference fit with the comers of the nut to lock the nut 20 against rotation. This particular locking structure is the subject matter of my copending application for Locking Cup Washer, Ser. No. 257,885, filed May 30, 1972, of common ownership with this application, which may be referred to if needed for a more detailed explanation of the locking function of the cup washer 24.

Thus, nut 20 determines the proper tightness of the bearings which support the vane 4 and the cap screw 30 serves to retain the actuating arm 26 and to lock the nut 20 against changes in its position.

In the structure illustrated in FIGS. 1 and 3, the inner bushing 8 is lodged in a circular counterbore or spot face 32 concentric with the bore 11, one such counterbore being provided for each vane. The disk 7 rotates wihin the counterbore with some radial clearance. The counterbore arrangement of FIGS. 1 and 3 to receive the bushing 8 is generally similar to prior art disclosures. It has the practical disadvantage that it is a slow and expensive operation to machine the very considerable number of counterbores required for the vanes of a stage of a typical compressor.

FIGS. 4 and 5 illustrate a structure which, while otherwise similar to the previously described, adopts a different arrangement of the interior of the compressor case and the inner bushing to avoid such expensive machining. In the structure of FIG. 4, parts corresponding to those previously described are marked with identical numerals. In this structure, the case 42 has a mounting ring or support 43 defining the outer flat surface 16 and bore 11 as previously described. The airfoil 6, disk 7, and shaft 12 may be as previously described. Bushings l4 and 15 may also be as in the other form. The difference lies in the fact that the interior of the case has a continuous circumferential recess 44 which is slightly undercut at its forward and rear ends to provide grooves 46 and 47 which extend circumferentially. In its preferred form, the inner bushing is made up of units 48 of generally rectangualr cross section which have central holes 50 for the bushing 14 and which occupy the entire width of the counterbore so as to have the edges received within the grooves 46 and 47. The bushings 48 have exterior surfaces corresponding to the cylindrical contour of the recess 44 and interior surfaces which are flat to mate with the outer surface of the disk 7 on the vane. The bushings may have-flanges 51 at their mutally adjacent ends. As will be apparent, the machining of the recess 44 can be a single turning operation in a boring mill or the like, which is a great deal easier and quicker to accomplish than provision of an individual counterbore 10 at each vane location. Since the bushings are molded of a suitable plastic material, it is a very simple matter to mold them to the desired shape.

If desired, a single integral strip may define a number of bushings 48, being provided with holes 50 at each vane position.

The assembly of the vanes into the case is very simple; the bushings 14 are disposed around the portion 13 of shaft 12 and the inner bushings 8 or 48 are laid against the outer surface of the disk 7 or inner surface of thecase. The shaft is then inserted through the case from the inside and outer bushing 15 and washer 18 are applied. Then nut 20 is tightened to provide the desired degree of tightness of the bushings. It will be understood that it is desired to minimize leakage and at the same time not to create undue resistance to rotation of the vane shafts. When this adjustment is completed, the washer 24, arm 26, and washer 31 are put in place and screw is tightened to hold these properly assembled.

At the time of this assembly, the arms 26 are preferably already coupled to a unison ring 60 by which the arms 26 are rotated in unison to adjust the vanes 4 concurrently. j

The preferred structure for connecting each arm 26 to ring 60 comprises a spherical bearing 62, the outer member of which is fixed to the outer end of arm 26 and the inner member of which is supported in the ring 60 by a hollow rivet 63, the ends of which are expanded into conical holes 64 in the channel section ring 60. A washer 66 may be provided to take up clearance between the inner member of bearing 62 and the unison ring 60. The ring 60 may be rotated about the axis of rotation of the compressor by any suitable mechanism, which need not be described here.

The advantages of the described structures, particularly that of FIGS, 4 and 5, over prior art structure should be apparent to those skilled in the art.

The detailed description of the preferred embodiment of the invention for the purpose of explaining the principles thereof is not to be considered as limiting or restricting the invention, since many modifications may be made by the exercise of skill in the art.

I claim:

1. A variable setting vane arrangement for a fluid dynamic machine comprising, in combination, an annular support; an annular cascade of vanes extending from the support, each vane including a disk at one end of the vane and a shaft extending from the disk in a direction spanwise with respect to the vane; the support having a ring of through holes and the shafts extending through the holes, the disks being on one side of the support; an abutment adjustable axially of the shaft threaded on each shaft on the other side of the support; bushing means disposed between the support and the disk, the shaft, and the abutment; locking means mounted on the shaft engageable with the abutment to hold the abutment against rotation; an actuating arm mounted on the said shaft portion operable to rotate the shaft to vary vane settingand engaging the locking means to retain the locking means; and a fastener securing the arm to the shaft.

2. A variable setting vane arrangement for a fluid dynamic machine comprising, in combination, an annular support; an annular cascade of vanes extending from the support, each vane including a disk at one end of the vane and a shaft extending from the disk in a direction spanwise with respect to the vane; the support having a ring of through holes and the shafts extending through the holes, the disks being on one side of the support; an abutment adjustable axially of the shaft threaded on each shaft on the other side of the support; resilient antifriction bushing means disposed between the support and the disk, the shaft, and the abutment; each shaft including a portion of noncircular crosssection at the opposite side of the abutment from the support; locking means mounted on the shaft engageable with the said shaft portion and the abutment to hold the abutment against rotation; an actuating arm mounted on the said shaft portion operable to rotate the shaft to vary vane setting and engaging the locking means to retain the locking means; and a fastener securing the arm to the shaft.

3. A variable setting vane arrangement for a fluid dynamic machine comprising, in combination, an annular support; an annular cascade of vanes extending from the support, each vane including a disk at one end of the vane and a shaft extending from the disk in a directionspanwise with respect to the vane; the support having a'ring of through holes and the shafts extending through the holes, the disks being on one side of the support; an abutment adjustable axially of the shaft threaded on each shaft on the other side of the support; resilient antifriction bushing means disposed between the support and the disk, the shaft, and theabutment; each shaft including a portion of noncircular crosssection at the opposite side of the abutment from the support; locking means mounted on the shaft engageable with the said shaft portion and the abutment to hold the abutment against rotation; an actuating arm mounted on the said shaft portion operable to rotate the shaft to vary vane setting and engaging the locking means to retain the locking means; a fastener securing the arm to the shaft; the said disks having a surface normal to the axis of the shaft confronting the support and the support having a circumferential recess defined in part by a continuous surface of revolution confronting the disks; and the bushing means including portions of generally rectangular outline disposed in the recess of thickness varying with the variation of clearance between each disk and the said surface of revolution.

4. A variable setting vane arrangement for a fluid dynamic machine comprising, in combination, an annular support; an annular cascade of vanes extending radially shaft confronting the support and the support having a cirucmferential recess defined in part by a continuous surface of revolution confronting the disks; and the bushing means including portions of generally rectangular outline disposed in the recess of thickness varying with the variation of clearance between each disk and the said surface. 

1. A variable setting vane arrangement for a fluid dynamic machine comprising, in combination, an annular support; an annular cascade of vanes extending from the support, each vane including a disk at one end of the vane anD a shaft extending from the disk in a direction spanwise with respect to the vane; the support having a ring of through holes and the shafts extending through the holes, the disks being on one side of the support; an abutment adjustable axially of the shaft threaded on each shaft on the other side of the support; bushing means disposed between the support and the disk, the shaft, and the abutment; locking means mounted on the shaft engageable with the abutment to hold the abutment against rotation; an actuating arm mounted on the said shaft portion operable to rotate the shaft to vary vane setting and engaging the locking means to retain the locking means; and a fastener securing the arm to the shaft.
 2. A variable setting vane arrangement for a fluid dynamic machine comprising, in combination, an annular support; an annular cascade of vanes extending from the support, each vane including a disk at one end of the vane and a shaft extending from the disk in a direction spanwise with respect to the vane; the support having a ring of through holes and the shafts extending through the holes, the disks being on one side of the support; an abutment adjustable axially of the shaft threaded on each shaft on the other side of the support; resilient antifriction bushing means disposed between the support and the disk, the shaft, and the abutment; each shaft including a portion of noncircular cross-section at the opposite side of the abutment from the support; locking means mounted on the shaft engageable with the said shaft portion and the abutment to hold the abutment against rotation; an actuating arm mounted on the said shaft portion operable to rotate the shaft to vary vane setting and engaging the locking means to retain the locking means; and a fastener securing the arm to the shaft.
 3. A variable setting vane arrangement for a fluid dynamic machine comprising, in combination, an annular support; an annular cascade of vanes extending from the support, each vane including a disk at one end of the vane and a shaft extending from the disk in a direction spanwise with respect to the vane; the support having a ring of through holes and the shafts extending through the holes, the disks being on one side of the support; an abutment adjustable axially of the shaft threaded on each shaft on the other side of the support; resilient antifriction bushing means disposed between the support and the disk, the shaft, and the abutment; each shaft including a portion of noncircular cross-section at the opposite side of the abutment from the support; locking means mounted on the shaft engageable with the said shaft portion and the abutment to hold the abutment against rotation; an actuating arm mounted on the said shaft portion operable to rotate the shaft to vary vane setting and engaging the locking means to retain the locking means; a fastener securing the arm to the shaft; the said disks having a surface normal to the axis of the shaft confronting the support and the support having a circumferential recess defined in part by a continuous surface of revolution confronting the disks; and the bushing means including portions of generally rectangular outline disposed in the recess of thickness varying with the variation of clearance between each disk and the said surface of revolution.
 4. A variable setting vane arrangement for a fluid dynamic machine comprising, in combination, an annular support; an annular cascade of vanes extending radially from the support, each vane including a disk at one end of the vane and a shaft extending from the disk in a direction spanwise with respect to the vane; the support having a ring of through holes and the shafts extending through the holes, the disks being on one side of the support; bushing means disposed between the support and the disk; and an actuating arm mounted on the shaft operable to rotate the shaft to vary vane setting; the said disks having a surface normal to the axis of the shaft confronting the support and the support having a cirucmferentiAl recess defined in part by a continuous surface of revolution confronting the disks; and the bushing means including portions of generally rectangular outline disposed in the recess of thickness varying with the variation of clearance between each disk and the said surface. 